Single piece top surface display layer and integrated front cover for an electronic device

ABSTRACT

A single-piece top surface display and integrated front cover for an electronic device. In one embodiment, the cover comprises a thin, flexible, transparent layer coupled with a supporting structure. The flexible layer is supported above a display screen which Is coupled with pressure activated sensors located under the display screen. The cover is dust-free, waterproof, and has a flat outer surface that is free of any steps or indentations. Users input data by applying pressure on the cover which causes the display screen to deflect and activate the sensors. The pressure exerted on the sensors is triangulated to register the position of the user input. In another embodiment, the cover is transparent, rigid, and directly contacts the pressure activated sensors which are located in front of the display screen or in the housing behind it. When pressure is applied to the cover, the cover deflects and activates the sensors. In both embodiments, an accelerometer identifies valid input events.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/758,888, filed Jun. 6, 2007, entitled SINGLE PIECE TOP SURFACEDISPLAY LAYER AND INTEGRATED FRONT COVER FOR AN ELECTRONIC DEVICE; whichis a continuation of U.S. patent application Ser. No. 09/863,706, filedMay 22, 2001, entitled SINGLE PIECE TOP SURFACE DISPLAY LAYER ANDINTEGRATED FRONT COVER FOR AN ELECTRONIC DEVICE, now U.S. Pat. No.7,348,964, issued Mar. 25, 2008; which is a continuation-in-partapplication of U.S. patent application Ser. No. 09/774,990, filed Jan.30, 2001, entitled INTEGRATED ENCLOSURE/TOUCH SCREEN ASSEMBLY; allaforementioned priority applications are hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of portable electronicdevices that contain display devices. More particularly, the presentinvention relates to devices that contain a touch screen assembly thatis activated by finger touch or by stylus pressure.

2. Prior Art

Advances in computer technology have enabled the further miniaturizationof the components required to build computer systems. As such, newcategories of computer systems have been created. One of the newercategories of computer systems is the portable, hand held, or “palmtop”computer system, also referred to as a personal digital assistant orPDA. Other examples of a portable computer system include electronicaddress books, electronic day planners, electronic schedulers and thelike.

A palmtop computer system is a computer that is small enough to be heldin the user's hand and as such is “palm-sized.” As a result, palmtopsare readily carried about in the user's briefcase, purse, and in someinstances, in the user's pocket. By virtue of its size, the palmtopcomputer, being inherently lightweight, 10 is therefore exceptionallyportable and convenient.

Flat panel resistive touch screen displays are found in numerouselectronic products such as wrist watches, hand calculators, cell phonesand PDA's both to present information to the user as well as tofacilitate input of data such as user touch screen commands. Suchdisplays include a resistive digitizer mechanism and a displaymechanism. A typical resistive digitizer mechanism consists of adigitizing element having a flexible thin film supported slightly abovethe surface of another thin layer digitizing element. A pressure appliedto the outer surface of the flexible film causes the film to deflect andcontact the digitizing element at a point which can be measured andthereby used as an input signal to activate the digitizer mechanism.

The flexible film and the digitizing element must be mounted in asupport housing to provide and maintain the proper spacing between thetwo. At the same time, additional protection against moisture, dust, andmechanical damage must be provided for the flexible film used in thedigitizer mechanism. Thus, an additional outer protective film mountedabove the digitizer flexible film is generally included in the touchscreen display assembly. The problem here is the reduction in thesensitivity to the external mechanical pressure required to activate thedigitizer mechanism. In addition, the added protective film may increaseoverall opacity which makes it more difficult to view any displayelement housed within.

Typically, a touch screen mechanism and a display mechanism are mountedwithin an enclosure in a recessed fashion. That is, the surface of theadditional protective film which actually forms the outer surface of thedigitizer mechanism is on a level below the outer edges of thesupporting enclosure which acts as a bezel. The display is mountedbeneath this digitizer mechanism. The resulting product then has a rimor step-down edge surrounding the touch screen which presents thetypical bezel-like appearance.

FIG. 1 is a cross-section view of an enclosure/touch screen assembly 100utilized in prior art. The entire assembly is held in place by thesupporting structure 105. The outer protective film 110 providesmechanical protection for the resistive digitizer film 120. In addition,the outer protective film is coupled to the support mechanism in orderto provide a moisture and dust seal. The digitizing element 130 islocated below and close to the digitizer film 120. An externally appliedpressure that deflects the protective film will also deflect thedigitizer film.

Any applied pressure great enough to cause the digitizer film to contactthe digitizing element will then activate the resistive digitizermechanism. The display element 140 is located below the digitizermechanism. User information is displayed on the upper surface of thedisplay element. Together, the protective film, the digitizer film andthe digitizing element must have an opacity small enough to allowviewing of the information displayed on the display element. The entiretouch screen assembly is located within the support structure such thatthe surface of the outer protective film is below the upper edge of thesupport structure. There is therefore a step-down corner 150 from 15 theupper edge of the support structure to the surface of the outerprotective film and the resulting assembly exhibits a bezel likeappearance. These step-down corners add thickness to the assembly, aredust and moisture collectors, are difficult to clean, and frequently donot seal properly. The electrical traces and electrodes 160, locatewhere the digitizer film and the digitizing element come 20 into contactwith each other. The metal frame 170, physically separates the touchscreen assembly from the display element.

One problem with the bezel design is that maintaining a moisture anddust-free environment for the touch screen mechanism is difficult. Suchan assembly often does not provide a satisfactory moisture and dustproof enclosure. An additional problem involves the complexity and costof assembly. Yet another problem involves the overall thickness of thedevice. The bezel design adds unwanted thickness to the displaycomponents. Additionally, some designers would like to eliminate thebezel to update the appearance of the device.

Another drawback is that, because of the amount of space between thetouch surface of the touch screen and display screen, there is what iscommonly referred to as the parallax effect. Simply stated, the parallaxeffect is a type of visual spatial distortion such that the actual pointof contact on the touch screen does not correspond to the intendedtarget area of the display screen. This is analogous to a stick beingimmersed in water, such that the stick takes on a bent or distortedappearance.

An additional drawback is that the amount of light that comes from thedisplay screen through the touch screen to be viewed by the user is onlyabout 80% of the available light. In a reflective display, that amountis further reduced to about 64%. This reduces the overall contrast,clarity, and quality of the display as seen by the user.

SUMMARY OF THE INVENTION

It would be advantageous, then, to provide a flat bezel-free displayinterface. Such an interface would reduce the possibility of damage toelectronic components from dust or water. It would also be advantageousto provide a display interface which reduces the parallax effect andpasses more light from the display to the viewer. The present inventionprovides a solution to meet the above needs.

Accordingly, embodiments of the present invention solve the problems ofparallax and reduced display quality seen in today's touch screendisplays. Embodiments of the present invention also eliminate the needfor the bezel usually seen with touch screen displays. The opticalproperties of the display are improved because the layers required forthe conventional analog resistive touch screens are eliminated.Embodiments of the present invention enable thinner construction. Theyimprove the optical performance of the display including powerefficiency, contrast, and brightness. These and other advantages of thepresent invention and others not specifically recited above will bedescribed in more detail herein.

Embodiments of the present invention include a single-piece integratedfront cover and display for an electronic device. In one embodiment, thecover consists of a thin flexible transparent outer layer coupled with asupporting structure. The flexible layer is supported above a displayscreen which is coupled with pressure activated sensors located behindthe display. The single-piece cover is dust-free, waterproof, and canhave a flat outer surface that is bezel-free, e.g., it is free of anysteps or indentations. Users input data by applying pressure on thecover which causes the display screen to deflect and activate pressuresensors. The pressure exerted on each sensor is measured to triangulatethe position of the user input.

In another embodiment, the cover is transparent, rigid, and extendsaround the display to directly contact the pressure activated sensors.The sensors may be located in front of the display, behind it, or may belocated in the housing. The display is coupled with the cover. Whenpressure is applied to the cover, the cover deflects and activates thesensors. In both embodiments, an accelerometer can be used forthresholding to identify valid input events. This display minimizes theproblems of parallax and reduced display brightness because the displayis seen without the intervening layer of the touch screen mechanism.

Embodiments of the present invention describe a display assembly for anelectronic device. The display assembly has a transparent cover above adisplay mechanism. Users can input data and commands by pressing on thiscover. The forces from the user inputs are mechanically transmitted topressure activated sensors. The sensors act in concert with anaccelerometer to locate the position of valid input events and translatethem into commands. In one embodiment of the present invention, thecover is a thin flexible outer film co-molded to a supporting structure.When the user presses on the cover, the display mechanism is deflectedand the force is transmitted to the sensors. In another embodiment, thecover is rigid and in direct contact with the sensors. When the userpresses on the cover, the force is directly transmitted to the sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of an enclosure/touch screen assembly utilizedin prior art.

FIG. 2A is a cross-section of an electronic device which utilizes asingle-piece integrated front cover and display in accordance with oneembodiment of the present invention.

FIG. 2B is a cross-section showing details of a thin flexible covercoupled with a supporting structure in accordance with one embodiment ofthe present invention.

FIG. 3 is a cross-section of an electronic device which utilizes asingle-piece integrated front cover and display upon which embodimentsof the present invention may be based.

FIGS. 4A and 4B show possible placements of pressure activated sensorsrelative to the display of a Personal Digital Assistant in accordancewith one embodiment of the present invention.

FIG. 5 shows the possible placement of pressure activated sensorsrelative to the display of a Personal Digital Assistant in accordancewith an embodiment of the present invention.

FIGS. 6A AND 6B show cross sections of a hand held computer andembodiments of the present invention illustrating where in molddecoration may be placed in the present invention.

FIG. 7 illustrates an exemplary computer system upon which 10embodiments of the present invention may be practiced.

DETAILED DESCRIPTION

A single-piece top surface display and integrated front cover for anelectronic device is described. While numerous details are set forth inorder to provide a thorough understanding of the present invention, itshould be understood that it is not intended to limit the invention tothis particular embodiment alone. On the contrary, the invention isintended to cover alternatives, modifications and equivalents, which maybe included within the spirit and scope of the invention as defined bythe appended claims. However, it will be obvious to one of ordinaryskill in the art that the present invention may be practiced withoutthese specific details. In other instances, well-known methods,procedures, components, and circuits have not been described in detailso as not to unnecessarily obscure aspects of the present invention.

FIG. 2A is a cross-section of an electronic device 200 which utilizes asingle-piece integrated front cover and display in accordance with oneembodiment of the present invention. A back cover assembly 210 enclosesand supports a circuit board 220. In the present embodiment of theinvention, the back cover assembly is a rigid molded plastic such as PC,PCABS, or ABS which will support and protect the internal electronics aswell as provide protection from dust, shock, and water. It isappreciated that there may be multiple circuit boards and that thesecircuit boards may be arrayed one above the other.

Outer film 230 is a single piece of bezel-less transparent flexiblethermoplastic that covers the entire top surface of a device such as aPersonal Digital Assistant. Numerous types of plastic exist which aresuited for this purpose, one of which may be a PET type plastic. In thepresent embodiment of the invention, outer film 230 is a flat surfacefree of any indentations. However, in another embodiment, outer film 230may have holes or indentations in some portion of the surface forbuttons or to indicate button or other like functions. Outer film 230 isflexible in that it has sufficient deflection that a user applying 10force on the surface of outer film 230 will be able to apply mechanicalpressure translated upon display mechanism 250. Outer film 230 isstretched over supporting structure 240.

Supporting structure 240 is, in the present embodiment of the invention,a rigid molded plastic such as PC, PCABS, or ABS and forms a perimeterframe around the top of the electrical device. Supporting structure 240may be co-molded with outer film 230 to form a single-piece front coverassembly which may form the top surface of the device. Supportingstructure 240 will also provide some method of securely attaching thefront cover assembly to back cover assembly 210, thus forming adust-proof and waterproof enclosure for the internal components ofelectronic device 200.

Electronic device 200 further includes a flat display mechanism 250which is disposed between outer film 230 and above sensors 260. Userdisplay information is displayed on the top of display mechanism 250.Display mechanism 250 may be a liquid crystal display, E-ink, organiclight emitting diode, field emission display, or other suitabletechnology used to create graphic images and alpha-numeric charactersrecognizable to a user. While display mechanism 250 is shown as being incontact with sensor 260 in FIG. 2, it may simply be in close enoughproximity that pressure applied to outer film 230 will cause it tocontact sensors 260. Sensors 260 are pressure activated sensors which,in concert with other pressure activated sensors, will be able toregister the position where force is applied to display mechanism 250.In this sense, sensors 260 are placed around the periphery of thedisplay 250 Sensors 260 are fixed to circuit board 220 which is in turnfixed to back cover assembly 210.

In one embodiment, the user will apply pressure to outer film 230 toindicate a particular position on display mechanism 250 that will inputa command to device 200. The pressure sensors 260 beneath displaymechanism 250 will be able to register where that position is bymeasuring the force exerted upon each sensor. At least three sensors maybe used, and a method such as triangulation will compare the relativeforces exerted and register where on display device 250 the pressure isexerted. An accelerometer (not shown) is coupled with the sensors toprovide pressure thresholding to differentiate a valid input frominvalid inputs that may result from, for example, dropping the device orcasual contact.

FIG. 2B is a cross section, showing in greater detail, the single-piecefront cover assembly of device 200. Outer film 230 is shown withsupporting structure 240 to form a single-piece front cover and displayfor device 200. Between the edge of supporting structure 240 and displaymechanism 250 is a small gap 270. This gap allows sufficient space sothat outer film 230 can come into contact with every part of the surfaceof display mechanism 250. If display mechanism 250 directly abuttedsupporting structure 240, there would be a small portion of the displaythat the user could not use as outer film 230 would not be able to comeinto contact with it. The gap may contain the traces and electrodes thatconnect with display mechanism 250 and be covered with a decorativeborder of some sort, e.g. in-mold decoration, to indicate where on 15device 200 the user should apply pressure.

FIG. 3 is a cross-section of an electronic device 300 which utilizes asingle-piece integrated front cover and display in accordance withanother embodiment of the present invention. A back cover assembly 310encloses and supports a circuit board 320. In the present embodiment ofthe invention, the back cover assembly 310 is a rigid molded plasticsuch as PC, PCABS, or ABS which will support and protect the internalelectronics as well as provide protection from dust, shock, and water.Again, it is appreciated that there may be multiple circuit boards andthat these circuit boards may be arrayed one above the other.

Device 300 is further comprised of pressure sensors 330. These arepressure activated sensors which are able to measure a force applied tothem. Front cover assembly 340 is shown in contact with pressure sensor330. Front cover assembly 340 is made of a transparent rigid plasticthat forms a single-piece top cover for device 300. It is formed totranslate around display device 350 to contact pressure sensor 330.Front cover assembly 340 is attached to back cover 310 to form adust-proof, waterproof, and shock resistant enclosure for the internalcomponents of device 300. While front cover assembly 340 is securelyattached to back cover 310, it has sufficient range of motion to allowmechanical transfer to pressure sensor 330. In this embodiment of theinvention, front cover assembly 340 is a single flat surface free of anyindentations, however, in another embodiment the front cover assemblymay have holes or indentations for buttons or to indicate button orother like functions.

The user will apply pressure to front cover assembly 340 to indicate aparticular position on display mechanism 350 that will input a commandto device 300. The pressure sensor beneath 330 will be able to registerwhere that position is by measuring the force exerted upon each sensor.At least three sensors may be used and a method such as triangulationwill compare the relative forces exerted and register where on displaydevice 350 the user is inputting a command. An accelerometer (not shown)is coupled with the sensors to provide pressure thresholding todifferentiate a valid input from invalid inputs that may result from,for example, dropping the device or casual contact.

FIGS. 4A and 4B show possible placements of pressure activated sensorsrelative to the display of a Personal Digital Assistant 400 inaccordance with one embodiment of the present invention. PDA 400 may becomprised of sensors 410, display area 420, display menu 430, anddisplay buttons 440. Additionally, FIG. 4B which illustrates anotherembodiment of the present invention in which indentations 450 arepresent. It should be noted that the sensors (410) are in both caseslocated beneath the front cover assembly.

In FIG. 4A, the sensors are placed in the outermost corners of thedevice. Display area 420 extends across the top surface of the device;display menu 430 and display buttons 440 are software generated featuresof display area 420 which is demarked by a visual line, not a bezeledge. Pressing on a software generated button will apply pressure to thedisplay mechanism (display mechanism, FIG. 2) which will in turntransmit that pressure to the sensors. The pressure exerted on each ofthe sensors is compared and the command that the user is indicating istriangulated. In FIG. 4B, the display mechanism does not extend acrossthe entire top surface of the device.

Indentations 450 are indentations in the one piece cover which indicatebutton functions to the user. Pressing on the indentation will activatethe pressure sensors as previously described.

FIG. 5 shows the possible placement of pressure activated sensorsrelative to the display of a Personal Digital Assistant 500 inaccordance with another embodiment of the present invention. PDA 500 iscomprised of sensors 510, display area 520, display menu 530, displaybuttons 540, and buttons 550. Display menu 530 and display buttons 540are software generated features of display area 520. Again, the sensorsare located beneath the front cover assembly. Buttons 550 are buttonsthat extend through holes in the one-piece cover assembly that willenable functions of the PDA but do not activate the sensors.

FIGS. 6A and 6B are cross sections of an exemplary hand held computerand embodiments of the present invention showing where in molddecoration may be placed in the present invention. FIG. 6A, illustratesan exemplary hand held computer which uses a resistive touch screenassembly and a display mechanism. The entire assembly is held in placeby the supporting structure 605. The outer protective film 610 providesmechanical protection for the resistive touch screen assembly which islocated above the display element 640. The touch screen assembly iscomprised of resistive digitizer film 620, digitizer element 630, andelectrical traces 650. An externally applied pressure that deflectsprotective film 610 will also deflect digitizer film 620. Any appliedpressure great enough to cause digitizer film 620 to contact digitizingelement 630 will then activate the resistive digitizer mechanism. Theelectrical traces 650 register the user input as a set of X/Ycoordinates.

Currently, the resistive element used with touch screen displays isIndium Tin Oxide (ITO). ITO is a relatively brittle material which, overtime, will break down. It is especially likely to fail at the pointwhere it is joined with the electrical traces 650. Because of this,digitizing element 630 is made rigid to prevent excessive flexing. Italso necessitates that the touch screen assembly be as flat as possiblewhich precludes the insertion of any in-mold decoration between thedisplay mechanism 640 and the digitizer mechanism.

In the present invention, the touch screen assembly is eliminatedbecause user input is detected by the pressure activated sensors. InFIG. 6B, sensors 650 indicate the position of pressure activated sensorsin an embodiment of the present invention in which a bezel-less,transparent, flexible thermoplastic is stretched over a supportingstructure. Sensors 660 show the placement of pressure activated sensorsin an embodiment of the present invention in which the cover is abezel-less, transparent, rigid, molded plastic. Decoration 680 is anin-mold decoration that may be placed between the top cover and thedisplay mechanism 670. Such placement is made possible because theweaknesses inherent with the touch screen design are avoided in thepresent invention.

FIG. 7 illustrates exemplary circuitry of portable computer system 700.Computer system 700 includes an address/data bus 701 for communicatinginformation, a central processor 702 coupled with the bus 701 forprocessing information and instructions, a volatile memory 703 (e.g.,random access memory RAM) coupled with the bus 701 for storinginformation and instructions for the central processor 702 and anon-volatile memory 704 (e.g., read only memory ROM) coupled with thebus 701 for storing static information and instructions for theprocessor 702. Computer system 700 also includes an optional datastorage device 705 (e.g., thin profile removable memory) coupled withthe bus 701 for storing information and instructions. Device 705 can beremovable.

As described above, system 700 also contains a signal communicationdevice 706, also coupled to bus 701. Signal communication device 706 canbe a serial port (or USB port) for communicating with a cradle (notshown). In addition to device 706, wireless communication links can beestablished between the device 700 and a host computer system (oranother portable computer system) using a Bluetooth wireless device 707or an infrared device 708. These devices are housed on a circuit board709 which is contained within a cover assembly.

Also included in computer system 700 of FIG. 7 is a display device 710.Display device 710 may be a liquid crystal display, field emissiondevice (FED, also called flat panel CRT), organic light emitting diode(OLED), E-ink, or any other display device suitable for creating graphicimages and alphanumeric characters recognizable to the user. In oneembodiment, the display 710 is a fiat panel multi-mode display capableof both monochrome and color display modes.

Device 700 also includes an alphanumeric input device 711 coupled withbus 701. In the present invention, the input device 711 comprises aplurality of pressure activated sensors and an accelerometer. Device 711can communicate information (spatial data and pressure data) and commandselections to the central processor 702. Device 711 is capable ofregistering a position on the screen 710 where contact is made and thepressure of the contact.

The preferred embodiment of the present invention, a single-piece topsurface display for a hand held computer, is thus described. While thepresent invention has been described in particular embodiments, itshould be appreciated that the present invention should not be construedas limited by such embodiments, but rather construed according to thebelow claims.

1. A display assembly for an electronic device comprising: a displaymechanism; a plurality of pressure activated sensors; and a single-piecebezel-less top cover enclosing said display mechanism to allowmechanical transfer between said top cover and said plurality ofpressure activated sensors, wherein said pressure activated sensors canbe activated by mechanical pressure applied to the external surface ofsaid single-piece cover enclosure.